<!Doctype html>
<html>
<head>
<meta charset="utf-8" />
<title>html5 image to base64</title>
</head>
<body>
<script type="text/javascript">
window.onload = function(){ 
// 抓取上传图片，转换代码结果，显示图片的dom
var img_upload=document.getElementById("img_upload");
var base64_code=document.getElementById("base64_code");
var img_area=document.getElementById("img_area");
// 添加功能出发监听事件
img_upload.addEventListener('change',readFile,false);}
function readFile(){
var file=this.files[0];
if(!/image\/\w+/.test(file.type)){ 
alert("请确保文件为图像类型"); 
return false; 
}
var reader=new FileReader();
reader.readAsDataURL(file);
reader.onload=function(){
base64_code.innerHTML = this.result; 
img_area.innerHTML = '<img src="'+this.result+'" alt=""/>'; 
}
}
</script>
<input type="file" id="img_upload"/>
<textarea id="base64_code" rows="30" cols="360" readonly="yes"></textarea>
<p id="img_area"></p>
</body>
</html>